Flame monitor

ABSTRACT

To grasp a state of a combustion apparatus based on a flame state of a burner, a discharge number measurement unit measures the number of discharges of a flame sensor per unit time, and a light emission information generation unit generates, as light emission information, information obtained based on a value obtained by dividing a total (accumulation) of the number of discharges per unit time measured by the discharge number measurement unit by a total measurement time, and a display unit displays the light emission information generated by the light emission information generation unit. Since the light emission information corresponds to a combustion amount, a change in a combustion state is capable of being grasped more finely by confirming a change in the light emission information displayed on the display unit, and a fine abnormality in a combustion apparatus is capable of being detected.

CROSS REFERENCE TO RELATED APPLICATIONS

This patent application claims the benefit of foreign priority to Japanese Patent Application No. JP 2022-007698 filed on Jan. 21, 2022, the disclosure of which is herein incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

The present disclosure relates to a flame monitor that measures a flame state of a burner.

In a combustion apparatus such as a combustion furnace, a drying furnace, and a boiler, a flame sensor that detects the presence or absence of a flame is used to control combustion in a combustion chamber. In general, an ultraviolet ray detection tube or the like is used as the flame sensor. The ultraviolet ray detection tube is a discharge tube in which, in a state in which a high voltage is applied between a pair of electrodes provided in a tube made of glass, discharge occurs between the electrodes when ultraviolet rays radiated from a flame are incident. A discharge current is obtained from the ultraviolet ray detection tube when the ultraviolet rays radiated from the flame are detected. A flame voltage obtained by integrating the discharge current and converting the discharge current into a voltage output is used for ignition control of a burner or the like (see PTL 1).

Incidentally, because a voltage to be applied to the flame sensor (ultraviolet ray detection tube) is generated from a commercial power supply voltage, a discharge current may also increase or decrease depending on a magnitude of a level of the power supply voltage and may not always be the same flame voltage. In order to eliminate an influence of fluctuation of the power supply voltage, a technique using a discharge probability calculated based on the number of times of application of a drive voltage to the flame sensor and the number of times of discharge from the flame sensor detected during the application of the drive voltage has been proposed (see PTL 2). The technique determines an ultraviolet ray intensity level based on the discharge probability.

CITATION LIST Patent Literature

[PTL 1] JP-A-2017-138018

[PTL 2] JP-A-2020-165830

BRIEF SUMMARY OF THE INVENTION

However, in the above-described related art, there is a problem that it is not easy to grasp a state of the combustion apparatus, such as what kind of abnormality occurred in the combustion apparatus, based on a flame state of the burner.

The present disclosure is made to solve the above-described problem, and an object of the present disclosure is to make it possible to grasp a state of a combustion apparatus based on a flame state of a burner.

A flame monitor according to the present disclosure includes: a flame sensor configured to detect ultraviolet rays generated from a flame; an application voltage generation unit configured to periodically apply a drive voltage to an electrode of the flame sensor; a discharge number measurement unit configured to measure the number of discharges of the flame sensor per unit time; a light emission information generation unit configured to generate, as light emission information, information obtained based on a value obtained by dividing a total of the number of discharges per unit time measured by the discharge number measurement unit by a total measurement time; and a display unit configured to display the light emission information.

In the above-described flame monitor according to one configuration example, the light emission information generation unit is configured to generate, as the light emission information, the value obtained by dividing the total of the number of discharges per unit time measured by the discharge number measurement unit by the total measurement time.

In the above-described flame monitor according to one configuration example, the light emission information generation unit is configured to generate, as the light emission information, a numerical value of an inclination of a graph of a linear function expressed by a formula in which the total of the number of discharges per unit time measured by the discharge number measurement unit is divided by the total measurement time.

In the above-described flame monitor according to one configuration example, the light emission information generation unit is configured to generate, as the light emission information, a graph of a linear function expressed by a formula in which the total of the number of discharges per unit time measured by the discharge number measurement unit is divided by the total measurement time.

As described above, according to the present disclosure, since the information obtained based on the value obtained by dividing the total of the number of discharges per unit time by the total measurement time is displayed as the light emission information, a state or a combustion apparatus can be grasped based on a flame state of a burner.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

FIG. 1 is a configuration diagram showing a configuration of a flame monitor according to an embodiment of the present disclosure.

FIG. 2A is a characteristic diagram showing a relation between a mixing degree (equivalence ratio) of combustion gas and air and a light emission intensity (light emission information).

FIG. 2B is a characteristic diagram showing a relation between the mixing degree (equivalence ratio) of the combustion gas and the air and the light emission intensity (light emission information).

FIG. 3 is a characteristic diagram showing measurement results of a flame voltage obtained by measurement of an ultraviolet ray detection tube.

FIG. 4 is a characteristic diagram showing a change in the number of discharges per 0.1 second obtained by measurement of the ultraviolet ray detection tube.

FIG. 5 is a graph of a linear function expressed by a formula in which a total of the measured number of discharges per unit time of the ultraviolet ray detection tube is divided by a total measurement time.

FIG. 6 is a configuration diagram showing a hardware configuration of a light emission information generation unit 104 of the flame monitor according to the embodiment of the present disclosure.

DETAILED DESCRIPTION OF THE INVENTION

A flame monitor according to an embodiment of the present disclosure will be described below with reference to FIG. 1 . The flame monitor includes a flame sensor 101, an application voltage generation unit 102, a discharge number measurement unit 103, a light emission information generation unit 104, and a display unit 105.

The flame sensor 101 detects ultraviolet rays generated from a flame 131. The flame sensor 101 may be constituted by, for example, an ultraviolet ray detection tube that detects ultraviolet rays in a predetermined wavelength range. The ultraviolet ray detection tube includes an anode electrode and a cathode electrode disposed in a tube made of glass.

The application voltage generation unit 102 periodically applies a drive voltage to the electrodes of the flame sensor 101. The application voltage generation unit 102 boosts, for example, a commercial alternating current voltage to be supplied from a power supply 106 to a predetermined value, and applies the commercial alternating current voltage to the electrodes of the flame sensor 101.

The discharge number measurement unit 103 measures the number of discharges of the flame sensor 101 per unit time. The discharge number measurement unit 103 measures, for example, the number of discharges of the flame sensor 101 per 0.1 second, and accumulates the measured values for a set time (unit time) to obtain the number of discharges of the flame sensor 101 per unit time.

When any voltage is applied between the anode electrode and the cathode electrode of the ultraviolet ray detection tube that constitutes the flame sensor 101, an electric field is generated between the anode electrode and the cathode electrode. In this state, when ultraviolet rays collide with the cathode electrode, secondary electrons are emitted from the cathode electrode.

The emitted secondary electrons are accelerated by the electric field and fly to an anode electrode side. At this time, the secondary electrons collide with molecules or ions between the electrodes, causing an avalanche phenomenon in which a large number of electrons are generated. The large number of electrons generated by the avalanche phenomenon travel in a direction of the anode electrode due to the electric field and reach the anode electrode. The phenomenon is a discharge in the ultraviolet ray detection tube. When the discharge occurs, the voltage between the anode electrode and the cathode electrode decreases, and a current is generated. The generation of the current is measured by the discharge number measurement unit 103 connected to the flame sensor 101 constituted the ultraviolet ray detection tube.

The light emission information generation unit 104 generates, as light emission information, information obtained based on a value obtained by dividing a total (accumulation) of the number of discharges per unit time measured by the discharge number measurement unit 103 by a total measurement time. For example, the light emission information generation unit 104 generates, as the light emission information, the value obtained by dividing the total of the number of discharges per unit time measured by the discharge number measurement unit 103 by the total measurement time. In addition, the light emission information generation unit 104 may generate, as the light emission information, a numerical value of an inclination of a graph of a linear function expressed by a formula in which the total of the number of discharges per unit time measured by the discharge number measurement unit 103 is divided by the total measurement time. In addition, the light emission information generation unit 104 may generate, as the light emission information, the graph of the linear function expressed by the formula in which the total of the number of discharges per unit time measured by the discharge number measurement unit 103 is divided by the total measurement time. Here, the linear function is an apparent linear (degenerated) function, and includes a case in which the inclination is zero.

The display unit 105 displays the light emission information generated by the light emission information generation unit 104 as described above. Since the light emission information corresponds to a combustion amount, a change in a combustion state can be grasped more finely confirming change in the light emission information displayed on the display unit 105. As a result, for example, a state of a combustion apparatus can be grasped based on a flame state of a burner. For example, a fine abnormality in the combustion apparatus can be detected.

For example, since rise of a flame voltage is delayed, the light emission information on the flame emitted from the burner cannot be determined by a change of the flame voltage, and ignition delay in an ignition operation in the combustion apparatus cannot be determined. In addition, since the flame voltage is output via a large number of filters due to a configuration of a circuit, it is difficult to grasp the change in the light emission information with the flame voltage in such a short period of time that the light emission information at the time of the ignition operation is difficult to determine.

Here, when a flow rate of combustion gas to be supplied to the burner is constant, it is considered that a mixing degree (equivalence ratio) of the combustion gas and air and a light emission intensity (light emission information) have relations as shown in FIG. 2A (Takeshi Kishimoto, Haruki Kinase, “Study on characteristics of a flame inspection sensor using ultraviolet band emission of hydrocarbon flame”, Commissioned Research by Yamatake Co., Ltd., Mar. 15, 2005). In addition, it is considered that these relations change as shown in FIG. 2B as the flow rate of the combustion gas changes.

In this way, when an amount of combustion gas supplied to the burner changes and an air ratio changes, the light emission intensity (light emission information) changes. In other words, the change in the light emission information indicates a change in the supply amount of the combustion gas or the air ratio. For example, a state in which the supply amount of the combustion gas or the air ratio is deviated from a reference indicates that there is a malfunction in a device to be managed or a control system that controls the supply amount of the combustion gas and the air ratio. Such a state is shown in the change in the light emission information.

According to the embodiment, since the change in the light emission information is displayed on the display unit 105, it is possible to grasp a sign of the malfunction or an abnormality of the device to be managed or the control system that controls the amount of combustion gas supplied to the burner and the air ratio in the combustion apparatus.

For example, a burner controller that controls the amount of the combustion gas supplied to the burner and the air ratio comes to a lockout stop when the abnormality occurs, and thus some equipment may stop operation. Although it is urgent to restore the equipment, a situation of burner peripheral equipment is complicated in the case of non-ignition and flame failure, and thus it often takes time to restore the equipment. Therefore, by making it possible to easily determine a sign of a failure of a combustion facility, it is possible to improve an efficiency of maintenance of the combustion facility and to shorten a restoration time at the time of abnormality.

For example, the combustion apparatus includes a pilot burner and a main burner, and between the ignition operation and steady combustion, there is an ignition period of the pilot burner as a first period, a firing period of only the pilot burner as a second period, and an ignition period of the main burner as a third period, and thereafter, there is a steady combustion period as a fourth period. Among these, a flame of the pilot burner (pilot flame) is present in the first period, the second period, and the third period, and a flame of the main burner (main flame) is present in the third period and the fourth period.

When the above-described state is applied to measurement results of the flame voltage obtained by the measurement of the ultraviolet ray detection tube, the state is as shown in FIG. 3 . The flame of the pilot burner is different from the flame of the main burner. Therefore, a flame voltage obtained by measurement of the ultraviolet ray detection tube for the flame of the pilot burner is different from a flame voltage obtained by measurement of the ultraviolet ray detection tube for the flame of the main burner. For example, as shown in FIG. 3 , the flame voltage differs between the first period and the second period when only the pilot burner is on and a second half of the fourth period when only the main burner is on.

However, since the flame voltage is output via a large number of filters due to a configuration of the circuit, there is a delay, and thus switching between the ignition period (third period) of the main burner and the fourth period when only the main burner is on is not apparent in the change of the flame voltage. In addition, as shown in FIG. 4 , even when a change in the number of discharges per 0.1 second is observed, the change looks like noise, and it is difficult to distinguish between the number of discharges by the pilot flame and the number of discharges by the main flame.

On the other hand, according to the embodiment, since the value obtained by dividing the total of the number of discharges measured per unit time by the total measurement time is generated as the light emission information, it is possible to distinguish between the number of discharges by the pilot flame and the number of discharges by the main flame by confirming the change For example, as shown in FIG. 5 , as expressed in the graph of the linear function expressed by the formula in which the total of the number of discharges measured per unit time is divided by the total measurement time, the number of discharges by the pilot flame and the number of discharges by the main flame are clearly seen. In this example, it can be seen that the output of the pilot flame is dominant (a large inclination) in the ignition period. In addition, as shown in FIG. 5 , when the inclination of the graph changes from a certain point, it means that the light emission intensity of the flame measured by the flame sensor changes at this point.

As shown in FIG. 6 , the light emission information generation unit 104 according to the above-described embodiment may be a computer device including a central processing unit (CPU) 301, a main storage device 302, an external storage device 303, a network connection device 304, and the like. The network connection device 304 is connected to a network 305. The CPU 301 operates (executes a program) by loading a program in the main storage device 302 of the computer device, thereby implementing functions of the light emission information generation unit 104.

As described above, according to the present disclosure, since the information obtained based on the value obtained by dividing the total of the number of discharges per unit time by the total measurement time is displayed as the light emission information, it is possible to grasp the state of the combustion apparatus, such as identifying an abnormality occurring in the combustion apparatus, based on the flame state of the burner. In the present disclosure, since the total of the number of discharges is used, there is no variation as a whole and an index is easy to handle, and for example, in a graph display, the inclination shows the light emission intensity, and thus it is easy to intuitively understand. The displayed light emission information can be used as an index for initial combustion adjustment, and can be used as an index for sensitivity correction when replacing a flame sensor.

The present disclosure is not limited to the above-described embodiment, and it is clear that various modifications and a combination thereof can be implemented by those skilled in the art within the technical idea of the present disclosure.

DESCRIPTION OF REFERENCE NUMERALS AND SIGNS

101: flame sensor, 102: application voltage generation unit, 103: discharge number measurement unit, 104: light emission information generation unit, 105: display unit, 106: power supply, 131: flame 

1. A flame monitor comprising: a flame sensor configured to detect ultraviolet rays generated from a flame; an application voltage generation unit configured to periodically apply a drive voltage to an electrode of the flame sensor; a discharge number measurement unit configured to measure the number of discharges of the flame sensor per unit time; a light emission information generation unit configured to generate, as light emission information, information obtained based on a value obtained by dividing a total of the number of discharges per unit time measured by the discharge number measurement unit by a total measurement time; and a display unit configured to display the light emission information.
 2. The flame monitor according to claim 1, wherein the light emission information generation unit is configured to generate, as the light emission information, the value obtained by dividing the total of the number of discharges per unit time measured by the discharge number measurement unit by the total measurement time.
 3. The flame monitor according to claim 1, wherein the light emission information generation unit is configured to generate, as the light emission information, a numerical value of an inclination of a graph of a linear function expressed by a formula in which the total of the number of discharges per unit time measured by the discharge number measurement unit is divided by the total measurement time.
 4. The flame monitor according to claim 2, wherein the light emission information generation unit is configured to generate, as the light emission information, a numerical value of an inclination of a graph of a linear function expressed by a formula in which the total of the number of discharges per unit time measured by the discharge number measurement unit is divided by the total measurement time.
 5. The flame monitor according to claim 1, wherein the light emission information generation unit is configured to generate, as the light emission information, a graph of a linear function expressed by a formula in which the total of the number of discharges per unit time measured by the discharge number measurement unit is divided by the total measurement time.
 6. The flame monitor according to claim 2, wherein the light emission information generation unit is configured to generate, as the light emission information, a graph of a linear function expressed by a formula in which the total of the number of discharges per unit time measured by the discharge number measurement unit is divided by the total measurement time.
 7. The flame monitor according to claim 3, wherein the light emission information generation unit is configured to generate, as the light emission information, the graph of the linear function expressed by the formula in which the total of the number of discharges per unit time measured by the discharge number measurement unit is divided by the total measurement time.
 8. The flame monitor according to claim 4, wherein the light emission information generation unit is configured to generate, as the light emission information, the graph of the linear function expressed by the formula in which the total of the number of discharges per unit time measured by the discharge number measurement unit is divided by the total measurement time. 